Headphones have improved a lot in terms of comfort and sound quality over the past century, but the basic concept hasn't changed. Attach them to an audio source, put them on or in your ears, and you'll hear sound via your eardrums.

But a new technology turns that old approach on its, well, head.

About a decade ago, VoxLinc designed a headphone for the military and law enforcement that conveyed sound to the listener through the cheekbones. Such bone-conducted audio reaches the cochlea directly, completely bypassing the eardrum. As a result there's no need to place anything on the ear that would block ambient noise.

Now VoxLinc is using the same bone-conduction technology in its AfterShokz headphones. AfterShokz even works for some hearing-impaired listeners, as long as the cochlea or the nerves around it are intact.

The phones wrap around the back of the head and rest just in front of the ears. They’re being marketed to bicyclists, who could then listen to tunes and still have their ears open to hear traffic. Although some might say that such potentially distracted cyclists have a lot of cheek.